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Sound travels fastest in a solid(metal) because the particles are closely packed and have high elasticity. This allows vibrations to pass from one atom to the next much faster than in liquids and gases, where the particles are far apart.

Parabolic mirrors (specifically concave parabolic reflectors) are designed so that when a light source is placed at their focal point, the reflected rays emerge as a tight, parallel beam

Parallel rays neither converge nor diverge. They remain the same distance apart and are considered to meet at infinity.

35o =35o = 70o 180 - 70 = 110 110/2 = 55o

A person with this condition is said to be short-sighted. Hence, to correct it, a concave lens is used for correction.

The pitch of a note depends on the frequency and wavelength of the source of the sound. a high-frequency (low wavelength ) produces a high-pitched note and a low-frequency ( high wavelength) produces a low-pitched note.

Magnification, M = v/u = v (1/u) And for the Lens formula 1/u + 1/v = 1/f => 1/u = 1/f - 1/v ∴M = V(1/u) = V(1/f - 1/v) = v/f - v/v = v/f - 1 ∴M = v/f - 1

From the above diagram ; ? = 90o - 30o = 60o v = 90 - 60 = 30 ∴ refractive index = (sin ?)/(sin v) = (sin 60o / sin 30o) = √3/2/1/2 = √3/2 x 1/2 = √3

When water freezes to ice, it undergoes anomalous expansion. Water's volume actually increases by approximately 9% as it turns into ice.

The phase difference between P and Q is \(\frac{\pi}{2}\)

Teapots are often silver-coated to prevent heat loss by reflecting infrared radiation. Silver is a good reflector of thermal radiation, which helps to minimize heat loss from the teapot, keeping the contents warm for a longer period.

No expanded working has been attached for this question yet. The verified answer is Option C.

Heat supplied by the heater in 10 mins = power x time = 50 x (10 x 60) = 30000 J This heat is equal = MCΔt = 5 x c x 12 = 60cJ = 60C = 30,000 C = 30,000/60 C = 500 J kg-1K-1

Safety gap = expansion of the rod = \(\alpha \times L_0 \times \Delta t\) where \(\alpha\) = linear expansivity of the material \(L_0\) = Initial length of the material \(\Delta t\) = Change in temperature \(\therefore\) The safety gap = \(2 \times 10^{-5} \times 20 \times (75 - 25)\) = \(2 \times 10^{-5} \times 10^3\) = \(2 \times 10^{-2} m\) = 0.02 m

Polarization is the only wave property that applies only to transverse waves.